People will also even put a credit card form on the site. See if people are actually willing to put down money. If you decide not to pursue the startup, just email them and tell them you are refunding their money.

(not OP) Yeah, something like that. Status updates or something, hopefully more involved than just no contact until shipped. You may want to use those people to help shape what you're building.

Exactly right. You'll want to work through some wording to get conversions, but also, that's a skill that you'll need to build anyway.